If I put the memory card from my camera or phone on a magnet, will it damage the data stored on there?
No.
The data on a card is stored with electrons, not with magnetized domains.
I suppose that if you waved the card next to the magnet at hyper-speed you could possibly induce enough EMF into the card to damage it, but that’s mostly science fiction.
So what about an electromagnet with alternating current?
Like a tape eraser? Nope.
So a hammer and a blowtorch it is then…
Oh, yeah.
That always works.
Or, stick in in a microwave oven.
You could try having really important data on it then dropping it on the floor somewhere. It will never be found again. (I’m assuming MicroSD.)
To be perfectly fair, the microwave does use magnetic fields. The hammer and blowtorch, too.
Sounds like the voice of bitter experience there
The scenario is someone with a full-size SD card containing data that would be bad to be caught with and no handy computer to wipe it with.
Just snap in in half, or cut it with a scissors, or poke a hole in it with an icepick, etc, etc.
It doesn’t take much to make the data irretrievable by anyone except the NSA, and even they would have problems.
Time and temperature can corrupt SD cards and solid state drives.
The charge in a memory cell can leak out. It seems that high temps can accelerate this. I read that it can happen in a few weeks if the temp is high. We have our operating systems on solid state drives in several locations. They are left to suffer high summer temperatures for months without being powered up. I have mentioned this as a problem.
Of course it isn’t a problem till the system does not boot up. Then I will be expected to solve it.
If you’re trying to erase it, then get a bit of software that can completely erase it, and then do whatever you want to damage it.
A NSA approved method of rendering HDDs unusable is with a cartridge-based nailer.. I bet they would be pretty effective on memory cards as well!
Or, with a hammer if you want to be boring.
Drop it in a glass of water and leave overnight. Or better still cook it in boiling water.